Self-supporting porous CoS2/rGO sulfur host prepared by bottom-up assembly for lithium-sulfur batteries

Abstract Cobalt disulfide (CoS 2 ) has been revealed as strong adsorption and activation sites for polar polysulfides, which effectively accelerates the redox reactions of polysulfides in lithium-sulfur (Li-S) batteries. As an ideal sulfur host, a three-dimensional (3D) graphene framework is adopted for high-performance Li-S batteries. Considering the special function of the CoS 2 nanoparticles and the advantages of a 3D porous graphene framework, a porous CoS 2 /reduced graphene oxide (CoS 2 /rGO) binder-free sulfur host is prepared by a bottom-up assembly and hydrothermal treatment. The porous rGO film is stacked by interconnected graphene sheets, and the CoS 2 nanoparticles are dispersed on the graphene sheets uniformly, which effectively obstructs the stacking of graphene sheets. As a binder-free sulfur host, the porous CoS 2 /rGO sulfur host combines the sufficient electron conductivity of the porous rGO framework and the sulfur immobilization interaction of the CoS 2 nanoparticles. This host material demonstrates an initial discharge capacity of 993.5 mAh g −1 and a capacity of 806.7 mAh g −1 after 110 cycles at 0.5 C. Both the capacity and cycling stability of the CoS 2 /rGO cathode were greatly improved over that of rGO. Furthermore, the bottom-up assembly approach provides a novel opportunity for preparing self-supporting graphene-based nanocomposite electrodes.